Infectious Disease

Leaked CDC document, new report warns of Delta contagiousness

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Walensky does not report any relevant financial information. Brown does not report any relevant financial information. Please refer to the study for all relevant financial information from the other authors.

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Rochelle P. Walensky

This week when she announced a stricter mask policy for vaccinated Americans, CDC director Rochelle P. Walensky, MD, MPH, said she saw data suggesting breakthrough infections caused by the Delta variant can be transmitted.

These data were published in a leaked internal CDC document and a new report published on the MMWR on Friday, warning of the contagiousness of the Delta variant, even in people fully vaccinated against COVID-19.

    Source: Adobe Stock

Source: Adobe Stock.

The leaked document, obtained from the Washington Post and the New York Times, states that the delta variant of SARS-CoV-2 is “as communicable as chickenpox,” and poses on a slide that says, “Next Steps for CDC “states that the agency must” acknowledge that the war has changed. ”

The CDC confirmed to Healio that the document was genuine.

Another slide points out that breakthrough cases caused by the delta variant “can be as transferable as unvaccinated cases”. The data to support this claim comes from two sources, according to the slide: the passive US surveillance, which showed a 10-fold increase in viral load in people with the Delta variant, and the new MMWR report, which showed no difference in Mean Cycle Threshold found values ​​in samples collected this month from vaccinated and unvaccinated individuals involved in an outbreak of infection-related public events in Barnstable County, Massachusetts.

“High viral loads indicate an increased risk of transmission and gave cause for concern that, unlike other variants, people infected with Delta can transmit the virus,” Walensky repeated in a new statement on Friday. “This finding is worrying and was a key discovery that led to the CDC’s updated mask recommendation. The masking recommendation has been updated to ensure that the vaccinated public does not unwittingly pass the virus on to others, including their unvaccinated or immunocompromised loved ones.

In the MMWR report Catherine M. Brown, DVM, an epidemiologist with the Massachusetts Department of Public Health, and colleagues summarized 469 cases of COVID-19 that have occurred in Barnstable County, where 69% of the population are fully vaccinated.

Of the 469 cases, about 90% were caused by Delta and 74% occurred in people who were fully vaccinated. Among those fully vaccinated with infection, 79% were symptomatic.

Five of the infected were hospitalized, including four fully vaccinated. No deaths were reported.

The report’s authors noted several of its limitations, including that the data “is insufficient to draw conclusions about the effectiveness of COVID-19 vaccines against SARS-CoV-2, including the Delta variant, during this outbreak”.

“As vaccination coverage increases at the population level, people who are vaccinated are likely to make up a greater proportion of COVID-19 cases,” the authors write.

They also noted that asymptomatic breakthrough infections may be underrepresented due to detection errors.

The leaked CDC document also indicates the rarity of breakthrough infections and that vaccination reduces the risk of serious illness or death by at least ten times and the risk of infection in vaccinated people by three times.

The leaked document also contains evidence that the Delta variant can cause more severe illness than other strains of SARS-CoV-2:

  • In Canada, it’s associated with a higher likelihood of hospitalization (adjusted OR [aOR] = 2.2; 95% CI 1.93–2.53), admission to the intensive care unit (aOR = 3.87, 95% CI 2.98–4.99) and death (aOR = 2.37; 95% CI 1 , 5-3.3).
  • In Singapore, it is more likely to have oxygen demand, ICU admission, or death (aOR = 4.9; 95% CI 1.43-30.78) and pneumonia (aOR = 1.88; 95% CI 0.95 -3.76).
  • Scotland: Greater likelihood of hospitalization (HR 1.85 [CI 1.39-2.47]).

References:

Abutaleb Y, et al. Washington Post. “The War Has Changed”: Internal CDC document calls for new messages and warns of likely more serious Delta infections. https://www.washingtonpost.com/health/2021/07/29/cdc-mask-guidance/. Accessed July 30, 2021.

Brown-CM et al. MMWR Morb Mortal Wkly Rep. 2021; doi: 10.15585 / mmwr.mm7031e2.

Mandavilli A. New York Times. The internal CDC report describes the Delta variant as being as contagious as chickenpox. https://www.nytimes.com/2021/07/30/health/covid-cdc-delta-masks.html. Accessed July 30, 2021.

Washington Post. Read: Internal CDC Document on Breakthrough Infections. https://www.washingtonpost.com/context/cdc-breakthrough-infections/94390e3a-5e45-44a5-ac40-2744e4e25f2e/. Accessed July 30, 2021.

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